1. Technical Field of the Invention
The invention relates to an electrical ignition method for combustion engines, wherein an arrangement of a plurality of electrical coils and a magnetic generator are used, which is coupled with the internal combustion engine via its crankshaft, for example, and rotates synchronously with it. In this context, the magnetic field of the magnetic generator flows intermittently through the coils and for each revolution a sequence of magnetic flux changes are generated. As a result, corresponding alternating voltage half-waves are induced in the coils.
The invention teaches that the alternating voltage half-waves in the ignition system are used for the following:    an energy storage element, for example an ignition capacitor, is charged with the alternating voltage half-waves and is discharged through actuation of an ignition switch via the primary coil windings of a pulse transformer for initiating an ignition spark for the cylinder or other combustion chamber of the combustion engine.    The alternating voltage half-waves are scanned, acquired, processed and/or evaluated and/or filtered by a microelectronic and/or programmable controller. An output result of this processing process consists in the determination of an ignition point in dependence from the acquired and evaluated alternating voltage half-waves and/or from another state of the combustion engine, for example from its rotational position or rotational speed. The ignition switch for generating an ignition spark is actuated according to the ignition point determined by the controller.    Furthermore, alternating voltage half-waves are at least partially supplied to the controller for its voltage and/or current supply.
The ignition of the gasoline/air mixture in the combustion chamber and/or cylinder of the combustion engine requires, as is actually known, a spark-over between the electrodes of the spark plug. For this purpose, a high charging voltage in the energy storage element, on the ignition capacitor, for example, is required. The charging voltage is dependent on the amplitude of the alternating voltage half-wave from the coil with which the energy storage element and/or the ignition capacitor is coupled. The amplitude height in turn depends on the rotational speed of the combustion engine. If this is low, the amplitude of the alternating voltage half-waves from the respective charging coil remains low, and the element and/or the ignition capacitor are charged correspondingly low. This circumstance can negatively affect the achievable starting speed range. In order to solve this problem, the effort in designing the magnet system and the charging coil could increase, which would mean higher manufacturing costs and require a larger installation space for the ignition system.
2. Prior Art
EP 1 691 053 A2 describes a control circuit for a capacitor discharge ignition system with a switch-off and/or coast down circuit. This responds during activation of a stop switch by discharging the ignition capacitor. By means of an RC [resistance-capacitance] delay element, the discharge of the ignition condenser is prolonged, whereby a storage of the charge for the next ignition pulse is prevented. EP 1 496 249 illustrates in its FIG. 15 that an ignition switch is controlled with a signal s4 via the complete rotation of the engine, in order to prevent the charging of the ignition capacitor by short-circuiting the positive charging coil half-waves (see output voltage section e1 of the output voltage E in FIG. 15a) even after the detection of the “switch-off state” (see stop time h1 in FIG. 15c) and also after the release of the switch-off switch 10 (see FIG. 12 there).
DE 10 2004 059 070 A1 (English language equivalent: U.S. Pat. No. 7,156,075 B2) describes an ignition method with a stop switch for combustion engines, in order to accomplish that they are switched-off and can coast down. The switch-off procedure is initiated with a pushbutton as a switching element. This stop switch prevents triggering the ignition. A controller arranged in the ignition circuit determines the state of the stop switch through evaluation of signals with respect to the state of the combustion engine. After releasing this pushbutton, it is necessary to ensure that no further ignition spark is generated until the engine has stopped. According to an alternative taught by this publication, the charging current is short-circuited by the ignition switch in order to prevent charging the ignition capacitor. With this ignition system, particular attention has been given to simplify and accelerate the restart or new start of the combustion engine. A new start should be possible immediately or still during the coast down of the engine. An alternative teaching is to prevent an actuation of the ignition switch which discharges the (charged) ignition capacitor, with the result that no further ignition sparks are generated any longer. To be precise, the drive pulse for the ignition switch is suppressed by the stop switch. Consequently, although the ignition capacitor continues to be charged also during the coast down, it will not be discharged, however. For the next (re-)start of the combustion engine, an already completely charged ignition capacitor can thus be available, which can be immediately discharged with the first revolution to generate an ignition spark.
If the ignition occurs at low rotational speeds too early before the top dead center (TDC) of the piston of the combustion engine, there is the risk of a kick-back [sic]. In the operating range and/or in normal continuous engine operation, advanced ignition points (in practice, approximately 15°-35° before TDC) are required in order to ensure optimum combustion, however. For remedy, refer to U.S. Pat. No. 5,069,193, EP 1 146 226 A2 and EP 1 178 208 A2. These publications teach that with increasing rotational speeds, the ignition point is increasingly advanced with respect to TDC. For this purpose, use is made of the effect that with increasing rotational speed and the associated increase in the magnetic generator angular velocity, the amplitudes and the slopes of the induced voltage half-waves become increasingly bigger. Due to the higher slope of the half-wave, a preset trigger voltage threshold for triggering the ignition with increasing speed is achieved earlier and/or faster. The precondition for this is that the first half-wave with each revolution is used for initiating the ignition triggering. Ignition systems according to the aforementioned patent publication, however, have the disadvantage that only with the first half-wave induction within the second revolution of the combustion engine, the ignition switch for discharging the ignition capacitor can be controlled, which was previously charged from the half-waves of the first revolution. During the first engine revolution, however, an ignition cannot be triggered because of the discharge which had previously occurred and/or due to the lack of charging of the ignition capacitor.
Furthermore, reference is also made to the older, European patent application 07 113 616.2 (English-language equivalent: U.S. patent application Ser. No. 12/183,092), the content of which is herewith incorporated into this application. In that older application, it is proposed that the ignition switch not be controlled beyond 360° or near 360° in the “switch-off” operating mode, but only in the angular ranges in which an ignition capacitor would be charged from the load coil or other coils. It is taught that within these limited angular ranges, the ignition switch be controlled either through a continuous pulse or through a burst and/or pulse repetition, where the intervals between the single pulses can be selected so far apart that the voltage value of the ignition capacitor is not increased to the extent that during the next switching on of the ignition discharge switch through the discharge of the ignition capacitor, a spark-over on the spark plug could be formed. For this purpose, FIG. 2-1c of the aforementioned old patent application is referred to. The duration of the intervals between the control pulses can be stored in the memory of the controller and have different values, depending on the rotational position and the rotational speed. In addition, it is proposed that below a certain rotational speed, in spite of switching-off the spark, the control of the ignition switch not be short-circuited but instead to no longer control the ignition switch. The rotational speed must be arranged sufficiently low so that the ignition capacitor is not charged with inadmissibly high voltages in spite of absent discharge processes, in order to avoid the risk of a dielectric breakdown in the ignition capacitor.